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Patented Oct. 24, 1882..

Inv'eniqr 17011185885 fla 7k Unirnn Sterne- PATENT @rrrca CHARLES E. SORIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGL MENTS, TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

, TELEPHONE-EXCHANGE SYSTEWL,

SPECIFICATION forming part of Letters Patent No. 266,821, dated October 24, 1882.

Application filed March 22, 1881. (No model.)

To all whom it may concern:

Be it known that I, CHARLES E. SGRIBNER, of Chicago, Illinois, have discovered certain 1 new and useful Improvements in Grouping Telephone-ExchangeCircuits,of which the following is a full, clear, concise, and exact de scription, reference being bad to the accompanying drawing, forming a part of this specification. V

The object of my invention is to provide for each subscriber a means of communication directly with the listening attendant atthecentral office at all times, for the purpose of obtaining a connection or disconnection, to enable the central-office manager to regulate at will the number of subscribers to be taken care of by a single attendant, and an improved method of notifying the attendant of a call when he is not listening at his telephone.

Heretofore a given subscriber has signaled the central office over his individual telephoneline, or by means of a separate circuit-wire running from the central otfice to all of the subscribers. The objection to these systems is that if the circuit-wire be broken none of the subscribers on that particular circuit can communicate their wants to the central office, nor can they obtain any service from the system until the damage is repaired. Another objec- 0 tion is that the central office has no means of varying the number of subscribers taken care of by a single attendant, and thus regulating the service at the central office so as to correspond to the demands of business at different 5 hours of the day, which is necessary in case there are more calls from a group of subscribers than one attendant can take care of.

' My invention consists in grouping the subscribers wires at the central office to a com- 0 mon wire, which connects to a listening operators telephone, and thence to ground, as hereinafter shown; in connecting the terminals of subscribers individual wires through call-bells subscribers, S, S S S and S are simply indicated. The first four subscribers lines, a, a (L 2tll(l a, are in one group and connected with jack-knife switches b b I) b and to the common wire 0 of the listening operators tele- 5 5 phone at the central office, while their outer ends are connnected by wire d. The second group of telephone-lines, e, 6 e and e, are connected in like manner through jack-knife switchesf,f ,f andf to common wire 9 of the listening operators telephone, and their outer ends are connected together by wire it.

It will be seen that by means of the switch t the two groups may be united and separated as occasion may require, and in likeimanner any number of groups of wires may be combined or divided, so that the service at the central office maybe adjusted at different hours of the day and at different seasons, in accordance with the demands of the subscribers.

7c and l are peg-switches,and m is an annunciator or bell in a line connecting with line 9 through a battery.

When there are very few demands on the central office the attendant may change the 7 5 peg from switch 70 to switch l and take telephone a from his ear. Now, when any subscriber of the group takes down his telephone the circuit will be closed to ground through the battery and annunciator m, and the listening operator will change the peg back to switch 70 and answer the call.

An automatic switch operated by the weight of the operators telephone may be used instead of the peg-switches 7c and Z.

The battery 0 is used primarily for calling up the subscribers asked for, but may be also used, as above indicated, to notify the listening operator that a subscriber has taken down his telephone. 1) is thelistening operators transmitter.

Each subscribers outfit consists of a transmitter, q, receiving--teleph0ne a", telephoneswitch s,call-bell t, and open-circuit contact or push-key a. 9 5

When the telephone-switch is brought by the weight of the telephone to position indicated by dotted lines, (see outfit of S,) the circuit of telephone-line amay be traced from the lever of switch 8 directly through the call-bell tto wired. ()n removing the telephone 1' from the hook the telephone-line a is changed, and may be traced from the switch-lever 8 through the receiving-telephone a and transmitter Q to ground. One point of the puslrkey a is connected with the common line d, the other point with the line by which the circuit of the line a is completed from the switch to the receiver. Ordinarily a subscriber has simply to take down his receiver and speak directly to the listening operator. Thus S is connected. directly with telephone a at the centralottice. Suppose, however, that the line a were open at the central ofiice. S, by pressing on push-key a, would immediately connect his telephone and transmitter with the listening operator by a circuit passing from the common line over the individual telephone-lines a and a ofthe group, or so manyof the group, whether one or a hundred, as might happen to be connected at the time with the common line d. Any subscriber may thus tall; directly to the listening operator over acircuit consisting of many telephonelines, connected at their outer ends with acommon wire and at the central oilicc with the common line of the listening operator. Each subscriber is thus provided with two circuits: first, his individual telephone-line; second, the lines of his group that happen to be connected with the common line at their outer ends when he connects with the said common line.

S and S are shown in private conn'nunication, connected through the central ollice by their telephone-lines a and e and the flexible cord 12, which, with the plugs, connects their respective switches I) and f. The central ofiice calls the subscriber asked for by inserting a plug connected with the calling-battery in his switch. Switch f is shown thus connected by flexible cord 10 with the calling-battery 0. The line 0 is thus cut ott' from the common ground-line g, and the circuit of the battery 0 may be traced from one pole by flexible cord 10 to switch 1", and by line c through the callbell of S, (the telephone of S is supposed to be hung on the switch, in the manner indicated by dotted lines, at station of S,) and thence to common line h, and by lines 0 and e of the group, or such lines as happen to be connected with line It, whether few or many, back to the central office to line 9, to which the other pole of the battery is connected.

In practice there will be many lines in the return -circuit, so that the current dividing through the call-bells of the return-wires will not be sufficient to ring the bell of a given line. As the current passes in one direction through the bell of the subscriber called and in the opposite direction through the bells of the wires of the return-circuit, the bells may be polarized to respond only to thecurrent passin gout from the central office, and thus the possibility of false signals being induced by the return-current may be effectually prevented, even though there might be but a single wire of the group in the return-circuit. \Vhen the subscribers are through talking, either one may close his push'key, and thus connect his outfit with the listening operator through the wires of his group that are at the time connected with the common wire of that group; or one subscriber may wait till the otherhangs up his telephone, and then tail: to the listening operator by a circuit composed of the two connected telephone-lines and the other wires of the group of the subscriber who has hung up his telephone. Suppose S has hung up his telephone so as to change his switch to the position in dicated by dotted lines at station of S. S may then talk to the listening operator at telephone a by the following circuit: beginning at ground, as indicated by G, at station of S and thence, as shown, through the transmitter and telephone to the telephone-switch, and thence by telephone-line a to switch 11, and thence to switch f, and by line 0 to the switch of S, and thence through the call-bell of S to common line h, and thence through the callbells of S S, 860., and their lines 0' a &c., to the common line 1, which passes through the listening operators telephonen and his transmitter p to ground, as shown. By this latter method the system may be worked successfully without the push-keys.

It will be seen two subscribers of the same group may be connected in the same manner, and that the number of subscribers in a group may be varied in accordance with the demands of business. A subscriber at all times has two chances of getting the central otlice. He has his individual line, which he will ordinarily use in the first instance; but it this line is not connected with the listening operator, by closing his push-key he has another circuit at his command.

I claim as my invention and desire to secure by Letters Patent- 1. The combination of telephone line a, switch b, ground-line 0,. telephone 0', switch 8, signal-instrument t, and common line (I with a return-circuit of such lines of the group as are at the time connected with line (I, substantially shown and described.

2. The circuit consisting of two subscribers telephone-lines, connected through the central oflice, one line being grounded at its terminal station, the other line connecting from the telephone-switch of its subscribers station-to a line common to the group, and one or more lines of the group connecting said common line with the line of the listening operator.

3. The circuit of a telephone-line, beginning at the common line of the listening operator and passing through a switch to a subscribcrs line, and thence to the telephone-switch of said subscribers station, and thence normally through the call-bell to a line common to the group of telephone-lines,and thence by one or more lines of said group to the said common line of the listening operator, in combination with a calling-battery in said circuit, substantially as shown and described.

4-. The combination of the group of subscribers lines a 0 0 &o., the wire 9, common to the ITO lines of the group, the line h, connecting the outer ends of thelines of the group, the battery 0, and switches f f f, &c., substantially as shown and described.

5. The groups of subscribers lines a M, 800., and 0 6 &c., normally connected at the central oflice through listeners telephone at to earth, in combination with lines 01 and h, substantially as shown and described.

6. Thetclephone-switch s,in combination with the subscribers line and the common line con-- necting the outer ends of the group.

7. Two or more groups of telephone-lines, each group in combination with an outer common line, and at the central office with a listening operators telephone and one or more switches, whereby the groups may be united or separated as occasion may require, substantially as and for the purpose specified.

8. The key to, combined with the circuit connecting subscribers telephone with common line (1, whereby the subscriber may close a circuit over the lines of the group connected with line (I to the ground-wire of the listening 0perator.v

9. The combination of the group oftelephonelines 0 e 0 850., the wire 9, common to the lines of the group, common line h, connecting the outer ends of the lines of the group, and the switches is l, or their equivalent, substantially as and for the purpose specified.

10. The combination of the switches s and at, under the control of the subscriber, with circuits, substantially as shown, whereby the subscriber may converse with the central office over his individual line, or by a circuit over one or more lines of the group to which his line belongs.

11. The switches s and u, signal-instrument t, and telephone 4 at subscribers station, in combination with individual line a. and common line d, substantially as and for the purpose specified.

12. The combination of key M with common wire at and subscribers line a.

13. The combination of a group of telephone lines with a common line connecting their outer ends, and polarizedbells, one at each subscribers station, responding to currents in but one direction.

CHARLES E. SOBIBNER.

Witnesses GEORGE P. BARTON, WILLIAM S. GRANGER. 

